Durable press cotton textile products produced conducting graft copolymerization process followed by cross-linking with dmdheu

ABSTRACT

This invention relates to a process for the preparation of durable-press cellulosic products. More particularly, this invention relates to a multistep process for the preparation of durable-press cellulosic products by a free radical initiated graft copolymerization process followed by a normal cross-linking process to yield products with high wash-wear ratings and high wrinkle recovery angles.

United States Patent Inventors Jett C. Arthur, Jr.;

James A. Harris; Trinidad Mares, all of Metairie, LI.

July 18, 1969 Sept. 21, 1971 The United States of America as represented by the Secretary of Agriculture Appl. No. Filed Patented Assignee DURABLE PRESS CO'I'ION TEXTILE PRODUCTS PRODUCED CONDUCTING GRAF'I' COPOLYMERI ZATION PROCESS FOLLOWED BY CROSS-LINKING WITH DMDHEU [56] References Cited UNlTED STATES PATENTS 3,254,939 6/1966 Munzel 8/ 1 16 OTHER REFERENCES Arthur et al., Textile Industries, Vol. 132, No. 9, pp. 77- 79, 81 (1968) Primary Examiner-George F. Lesmes Assistant Examiner-4. Cannon Attorneys-R. Hoffman and W. Bier ABSTRACT: This invention relates to a process for the preparation of durable-press cellulosic products. More particularly, this invention relates to a multistep process for the preparation of durable-press cellulosic products by a free radical initiated graft copolymerization process followed by a normal cross-linking process to yield products with high washwear ratings and high wrinkle recovery angles.

DURABLE PRESS COTTON TEXTILE PRODUCTS PRODUCED CONDUCTING GRAFT COPOLYMERIZATION PROCESS FOLLOWED BY CROSS-LINKING WITH DMDHEU A nonexclusive, irrevocable, royalty-free license in the inventicn herein described, throughout the world for all purposes of the United Ftates Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to a multistep process for the preparation of durable press cotton textile products, wherein (l) the macromolecular properties of the cotton cellulose and the morphological structure of cotton are selectively and permanently changed by a free radical initiated graft copolymerization process and then (2) the modified cotton is cross-linked to yield all cotton textile products with higher wash-wear ratings and wrinkle recovery angles than unmodified cotton products which have only been cross-linked. The method of this invention has as its objective the modification of both the chemical and physical structures of cotton fibers, mechanically organized into both fabrics suitable for trouser and/or shirting garments, so that the natural properties of cotton are conserved to a maximum extent while imparting durable press properties to the resulting all cotton textile products.

The manufacture of durable press all cotton textile products has been severely limited due to the fact that when cotton is reacted with finishes which impart high wrinkle recovery angles to cotton products prohibitive decreases in natural properties of cotton textile products, such as decreases in abrasion resistance, tearing strength, and wash-wear performance ratings, are obtained. Generally, manufacturers have blended manmade fibers with cotton fibers prior to finishing to give textile products with good wrinkle recovery angles, abrasion resistance, tearing strength, and wash-wear performance ratings. Cotton is included in the blends, usually comprising less than 35 percent of the finished fabric because of its desirable natural properties, such as its moisture sorption and desorption properties, which add to the comfort of textile garments, and its chemical reactivity toward finishing agents, generally cross-linking agents, which impart increased wrinkle resistance to the products. The presence of manmade fibers probably assists in the retention of tearing strength and abrasion resistance by the products.

Developments in using free radical initiators for copolymerizing vinyl monomers with cellulose have offered the possibility of modifying the macromolecular properties of cellulose with minimum decrease in the chemical reactivity of the modified cellulose toward cross-linking reagents. One of the promising methods for free radical initiation of the copolymerization reaction ionizing vinyl monomers is the interaction of ionizing radiation with cotton to produce longlived free radical sites on the cellulose molecule. The number of free radical sites on the cellulose molecule can be controlled by the radiation dosage, that is, time of exposure of the cotton fabric to a given source of ionizing radiation. So that after macromolecular properties of the cellulose molecule and morphological properties of the cotton fibers are selectively altered, the chemical reactivity of the cellulose molecule is not greatly reduced toward cross-linking reagents. Therefore, (I) in one step, the cotton fabrics are exposed to ionizing radiation to give a desired number of free radical sites on the cellulose molecule; (2) in a second step, which may be immediately after or several days after exposure of the fabric to ionizing radiation, the activated cotton fabrics are immersed in a solution of vinyl monomer for a predetermined time to give the desired degree of copolymerization of the activated cellulose with the vinyl monomer to alter the macromolecular properties of the cellulose and to change selectively the morphological properties of the cotton fibers; and (3) in a third step, treatment of the cellulose-graft copolymer fabric with crosslinking reagents to give all-cotton durable press products, with improved wash-wear performance ratings and related properties.

The instant invention defines a distinct improvement in selectively and permanently changing the morphological structure of the cotton fibers in the fabrics. Using ionizing radiation to produce long-lived free radicals on the cellulose molecule, solvents for the vinyl monomer can be selected which do not cause dimensional changes in the cotton fibers, maintaining the natural shape of the fibers. In this case, the grafted copolymer can be formed primarily in the outer layers of the fibers. On the other hand, solvents for the vinyl monomers can be selected which cause dimensional changes in the fibers, that is, swelling and rounding of the cross section of the fibers. ln this case, depending on the vinyl monomer selected, the grafted copolymer can be formed in the outer layers of the fibers, uniformly within the fibers, or within the fibers while causing a layering effect. The molecular relationships between the cellulose molecule and grafted copolymer are such that the chemical reactivity of cellulose toward crosslinking reagents remains high. The moisture sorption and desorption properties of the resulting cotton product, based on the content of cellulose, is about the same as untreated cotton.

The following examples set forth the invention in more detail.

EXAMPLE 1 Cotton twill fabric was dried to less than 2 percent moisture in a vacuum oven at 50 C., sealed in a nitrogen atmosphere in a thin metal container, and irradiated to a dosage of l megarad by cobalt-6O gamma-radiation. Four days later the radiation-activated fabric was immersed in a solution comprising acrylonitrile (15 parts by volume), dimethylsulfoxide (25 parts), and water 15 parts) at 25 C. in the absence of oxygen for 7 minutes to give 8 percent add-on of poly(acrylonitrile). The graft copolymerized fabric was washed and dried in air and then treated with cross-linking agent, dimethylol dihydroxyethylene urea (DMDHEU) in the usual manner to give an add-on of 7-9 percent, dried in an air oven followed by pressing on a hot head steam press, and then cured in a forced draft oven at C. for 12 minutes. The breaking strength of the grafted and cross-linked fabric was 65 pounds (raveled strip method), tearing strength 1300 grams (Elmendorf method), fiex abrasion resistance (American Society for Testing Materials method) 420 cycles, and flat abrasion 520 cycles. Values for cross-linked fabric was, respectively, 46 pounds, 1070 grams, 220 cycles, and 290 cycles.

EXAMPLE 2 The method of example 1, except that the radiation-activated fabric was immersed in the monomer solution for 25 minutes to give 19 percent add-on of poly(acrylonitrile). The properties of the grafted and cross-linked fabric and of the cross-linked fabric were, respectively: breaking strength, 73 pounds and 46 pounds; tearing strength, l270 grams and l070 grams; flex abrasion resistance, 370 cycles and 220 cycles; fiat abrasion resistance, 590 cycles and 290 cycles.

EXAMPLE 3 The method of example 1, except that after grafting, crosslinking drying, and pressing, simulated trouser cuffs were made, pressed on a hot head steam press, and then cured in a forced draft oven at 160 C. for 12 minutes. After thirty washing and drying cycles in commercially available washers and dryers, the trouser cuffs were rated for appearance (American Association of Textile Chemists and Colorists Test Method No. 124) on a scale from 1 to 5, Cuffs, cross-linked only, had an appearance rating of 4.0; cuffs, grafted and cross-linked had an appearance rating of 4.5.

EXAMPLE 4 The method of example 1, except that 7 days after radiation activation of the twill fabric, it was immersed in a solution comprising methyl methacrylate (15 parts by volume), methanol (45 parts), and water (40 parts) at 25 C. in the absence of oxygen for 2.5 minutes to give l4 percent add-on of poly(methyl methacrylate). The graft copolymerized fabric was washed and dried in air, treated with crosslinking agent DMDHEU in the usual manner to give an add-on of 7-9 percent, and then dried in an air oven, followed by pressing on a hot head steam press. Simulated trouser cuffs were made, pressed on a hot head steam press, and then cured in a forced draft oven at 160 C. for 12 minutes. After thirty washing and drying cycles, trouser cuffs cross-linked only had an appearance rating of 4.0; cuffs, grafted and cross-linked, had an appearance rating of 4.5. When the grafting reaction times were 5 minutes and 9 minutes, add-ons of poly(methyl methacrylate) were 17 and 30 percent, respectively; after 30 washing and drying cycles trouser cuffs, grafted for these times and later cross-linked had appearance ratings of 4.5 and 4.6, respectively.

Example 5 absence of oxygen for 6 minutes to give 6 percent add-on of poly(butyl methacrylate). The graft copolymerized fabric was washed and dried in air, treated with cross-linking agent DMDHEU in the usual manner to give an add-on of 7-9 percent, and then dried in an air oven, followed by pressing on a hot head steam press. Simulated trouser cuffs were made, pressed on a hot head steam press, and then cured in a forced draft oven at 160 C. for 12 minutes. After 30 washing and drying cycles, trouser cuffs cross-linked only had an appearance rating of 4.0; cuffs, grafted and cross-linked had an appearance rating of 4.6. When the grafting reaction times were I 1 minutes and 16 minutes, add-ons of poly(butyl methacrylate) were l0 and percent, respectively; after thirty washing and drying cycles trouser cuffs, grafted for these times and later cross-linked had appearance ratings of 4.6 and 4.2, respectively.

EXAMPLE 6 The method of example I except that 7 days after radiation activation of the twill fabric, it was immersed in a solution comprising lauryl methacrylate (20 parts by volume) and methanol (80 parts) at C. in the absence of oxygen for minutes to give 4 percent add-on of poly(lauryl methacrylate). The graft copolymerized fabric was washed and dried in air, treated with cross-linking agent DMDHEU in the usual EXAMPLE 7 The method of example 1 was followed, except that cotton printcloth fabric was used. Conditioned wrinkle recovery angle, warp plus fill (Monsanto method) for printcloth fabric cross-linked only was 274 (360 being complete recovery); printcloth fabric grafted with poly(acrylonitrile) and then cross-linked gave at 9 percent grafted polymer add-on, 293; at l 1 percent, 296; at 18 percent, 304.

EXAMPLE 8 The method of example 4 was followed, except that cotton printcloth fabric was used. Conditioned wrinkle recovery angle for printcloth fabric crosslmked only was 274; printcloth fabric grafted with poly(methyl methacrylate) and then cross-linked gave at 13 percent grafted polymer add-on; at 20 percent, 31 1; at 27 percent, 307.

EXAMPLE 9 The method of example 5 was followed, except that cotton printcloth fabric was used. Conditioned wrinkle recovery angle for printcloth fabric cross-linked only was 274; printcloth fabric grafted with poly(butyl methacrylate) and then cross-linked at 4 percent grafted polymer add-on, 311; at 8 percent, 292; at 15 percent, 293.

We claim:

1. A process for preparing durable press cellulosic products which process comprises:

a. drying a cellulosic fabric to about a 2 percent moisture content,

b. irradiating the fabric to a dosage of about 1 megarad,

c. copolymerizing the radiation-activated fabric in the absence of oxygen with a vinyl monomer selected from a group consisting of acrylonitrile, methyl methacrylate, butyl methacrylate, and lauryl methacrylate,

d. washing the copolymerized fabric from (c) free of excess reagents and drying the washed fabric, and

e. cross-linking the dried fabric from (d) with dimethylol dihydroxy ethylene urea.

2. The product produced by the process of claim 1. 

2. The product produced by the process of claim
 1. 